Slowdown detection

ABSTRACT

One or more techniques and/or systems are provided for slowdown detection. Location data received from vehicles traveling a road is evaluated to identify a road segment associated with vehicle speeds below a threshold. A space-time diagram is generated, and location data associated with vehicles traveling the road segment are plotted within the space-time diagram. The space-time diagram is processed using a convolutional neural network to determine a probability that the space-time diagram illustrates a slowdown. If the probability that the space-time diagram illustrates the slowdown is greater than a threshold, then a notification of the slowdown is transmitted to one or more computing devices associated with vehicles that may encounter the slowdown.

RELATED APPLICATIONS

This application claims priority to U.S. patent application Ser. No.16/525,658, filed on Jul. 30, 2019 and titled “SLOWDOWN DETECTION,”which claims priority to U.S. Provisional Patent Application No.62/754,208, filed on Nov. 1, 2018 and titled “SLOWDOWN DETECTION,” whichare incorporated herein by reference.

BACKGROUND

Slowdowns can occur quickly and without warning along a road. A slowdownis where vehicles are rapidly slowing down in a short distance withlittle warning due to various conditions (e.g., congestion due todrivers braking to look at a car accident). Slowdowns can lead toserious accidents because drivers must slow vehicles down quickly withina short distance due to having little to no forewarning of the need toslowdown. Thus, it is imperative to provide drivers with warnings ofslowdowns in a timely manner so that drivers can perform preventativeactions.

SUMMARY

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the detaileddescription. This summary is not intended to identify key factors oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter.

Among other things, one or more systems and/or techniques for slowdowndetection are provided. In an embodiment, location data, such as globalpositioning system (GPS) data, is received from vehicles traveling aroad. The location data is evaluated to identify a road segmentassociated with vehicle speeds below a threshold of speed (e.g., roadsegments where vehicles are traveling a threshold amount slower than aspeed limit).

A space-time diagram is generated based upon the location data receivedfrom the vehicles. Location data of the road segment and/or surroundingroad segments may be used to generate the space-time diagram. A firstaxis of the space-time diagram represents distance along the roadsegment(s) and a second axis of the space-time diagram represents time.Location data associated with vehicles traveling the road segments(s) isplotted within the space-time diagram. In this way, the space-timediagram represents locations of cars along the road segment(s) overtime, which is referred to as vehicle trajectories that are indicativeof vehicle speeds. A vehicle trajectory of a vehicle corresponds tolocation data of the vehicle plotted within the space-time diagram. Themore horizontal a vehicle trajectory (e.g., the more parallel to thefirst axis representing distance along the road segment(s)), the fastera vehicle is traveling. The more vertical a vehicle trajectory (e.g.,the more parallel to the second axis representing time), the slower thevehicle is traveling. Also, colors may be assigned to vehicletrajectories based upon ranges of vehicle speeds, such as a green color(or any other color) for free flowing vehicles that are traveling closeto the speed limit and a red color (or any other color) for congestedflow vehicles traveling well below the speed limit.

Machine learning functionality (e.g., a convolutional neural network orany other neural network or machine learning or imageprocessing/recognition/classification) is executed to process thespace-time diagram to output probabilities of whether the space-timediagram illustrates a slowdown or whether the space-time diagram doesnot illustrate a slowdown. In an embodiment, a convolutional neuralnetwork has been trained to utilize image recognition functionality todetect whether space-time diagrams illustrate slowdowns of vehiclesbased upon trajectories of vehicles, colors of vehicle trajectories,and/or features extracted from the space-time diagram (e.g., slopes oftrajectories indicating vehicles speeds, changes in slopes oftrajectories indicating quick/sharp vehicle speed changes, shapefeatures, length and size features, etc.).

In an embodiment, the probabilities are above a threshold indicative ofa slowdown, then recent location data of vehicles traveling the roadsegment(s) are clustered such as by using a k-means clustering algorithmon GPS vehicle speed data. In an embodiment, a regression convolutionalneural network, trained to detect pixels within space-time diagramsrepresenting transition points (e.g., back end of queue of a slowdown),is executed to identify a current transition point between free flowvehicle traffic and congested flow vehicle traffic. The transition pointis used to separate vehicle speeds into separate clusters (e.g., a firstcluster of vehicle speeds obtained before the vehicles reach thetransition point and a second cluster of vehicle speeds obtained afterthe vehicle reached the transition point). A difference between a firstmedian of a first cluster of free flow vehicle speeds and a secondmedian of a second cluster of congested flow vehicle speeds isdetermined. A dangerous slowdown is detected if the difference incluster medians exceeds a speed threshold.

Outlier vehicle speeds may be removed from the clusters, such as byusing a Hampel filter. A difference between a median of a cluster ofslow vehicle speeds and a median of a cluster of free flowing vehiclespeeds is identified. If the difference exceeds a threshold, then theslowdown, such as a dangerous slowdown, is detected. The clusters andthe medians can be used to identify a precise location of the slowdownalong the road segment(s). A notification can be transmitted to vehiclestraveling routes that will encounter the slowdown while the slowdown ispredicted to be occurring. The notification can comprise the location ofthe slowdown, an alternative route that avoids the slowdown, audibleand/or visual warnings, a predicted end time that the slowdown ispredicted to dissipate, a time of the slowdown, a predicted new locationof a backend queue of vehicles slowed down by the slowdown, and/or otherinformation.

To the accomplishment of the foregoing and related ends, the followingdescription and annexed drawings set forth certain illustrative aspectsand implementations. These are indicative of but a few of the variousways in which one or more aspects may be employed. Other aspects,advantages, and novel features of the disclosure will become apparentfrom the following detailed description when considered in conjunctionwith the annexed drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow diagram illustrating an exemplary method of slowdowndetection.

FIG. 2 is an illustration of a space-time diagram that illustrates aslowdown.

FIG. 3 is an illustration of a space-time diagram that illustrates aslowdown.

FIG. 4 is an illustration of a space-time diagram that illustrates aslowdown.

FIG. 5 is an illustration of a space-time diagram that does notillustrate a slowdown.

FIG. 6 is an illustration of a space-time diagram that does notillustrate a slowdown.

FIG. 7 is a component block diagram illustrating an exemplary system forslowdown detection.

FIG. 8 is an illustration of an exemplary computing device-readablemedium wherein processor-executable instructions configured to embodyone or more of the provisions set forth herein may be comprised.

FIG. 9 illustrates an exemplary computing environment wherein one ormore of the provisions set forth herein may be implemented.

DETAILED DESCRIPTION

The claimed subject matter is now described with reference to thedrawings, wherein like reference numerals are generally used to refer tolike elements throughout. In the following description, for purposes ofexplanation, numerous specific details are set forth in order to providean understanding of the claimed subject matter. It may be evident,however, that the claimed subject matter may be practiced without thesespecific details. In other instances, structures and devices areillustrated in block diagram form in order to facilitate describing theclaimed subject matter.

One or more computing devices and/or techniques for slowdown detectionare provided. Current technological processes for detecting slowdownsare imprecise and result in many false positives where a slowdown isdetected when there is none or no slowdown is detected when there isone. Alerting drivers of slowdowns when there is no slowdown isdisruptive and can disrupt the free flow of traffic because vehicleswill attempt to preemptively slowdown for the slowdown even though thereis no actual slowdown. When drivers are not alerted of slowdowns, thenserious accidents can result from drivers being unaware of quicklyoccurring slowdowns without warning. Current technological processes areimprecise because they merely search for slowdowns based upon whetherdata indicates that a speed difference between a road segment and anupstream road segment is greater than a threshold. Such techniques arealso unable to locate precise locations of slowdowns, and may merelyattempt to locate a slowdown between 2 road segments even though theslowdown may occur anywhere within one of the road segments.

Accordingly, as provided herein, conventional technological processesfor detecting slowdowns are improved by processing location data ofvehicles to generate a time-space diagram that is processed usingmachine learning such as a convolutional neural network or any othermachine learning technique to determine whether the time-space diagramillustrates a slowdown. This improves the precision of detectingslowdowns so that drivers can be alerting in a timely manner to improvetraffic safety without providing false positives that decrease trafficsafety and/or hinder the flow of traffic.

In an embodiment, a particular type/degree of slowdown, such as adangerous slowdown, a moderate slowdown, a continuous spectrum ofdifferent degrees of slowdowns, etc. is detected. A type/degree ofslowdown may be detected based upon certain properties of the slowdown,the time-space diagram, and/or vehicle location/speed data. For example,a dangerous slowdown is detected if a difference between free flowingtraffic speed and congested flow traffic speed (e.g., a transition fromfree flowing to congested flow traffic, such as a backend of queue ofthe slowdown where vehicle are abruptly slowing down) is greater than athreshold such as 65 kph or any other threshold speed value. A dangerousslowdown relates to a lack of opportunity for a driver to adequatelyslowdown in time, which can be identified by slopes of vehicletrajectories within the space-time diagram that correspond to certainamounts of deceleration over short distances. In another example, acontinuous spectrum or multiple types/degrees of slowdowns can beidentified (e.g., very dangerous slowdown corresponding to 70 kph, adangerous slowdown corresponding to 65 kph, a moderately dangerousslowdown corresponding to 50 kph, etc.), where each type of slowdowncorresponds to a degree or severity of danger of a slowdown. Thedifferent degrees/types of slowdowns can be identified based upondifferent threshold speed values or slopes of vehicle trajectories(e.g., a steeper slope may be indicative of a more dangerous type ofslowdown).

An embodiment of slowdown detection is illustrated by an exemplarymethod 100 of FIG. 1, and is described in conjunction with system 700 ofFIG. 7. Location data 702 is received from vehicles traveling alongroads over time. For example, GPS data, indicative of location and/orspeed of vehicles, is received over a network from GPS devices of thevehicles. At 102, the location data is evaluated to identify a roadsegment associated with vehicle speeds below a threshold. In anembodiment, a plurality of road segments having vehicle speeds below thethreshold are identified as candidate road segments for furtherprocessing to determine whether such road segments are experiencingslowdowns. The threshold may be an adjustable threshold that is basedupon a speed limit of individual road segments. Thus, vehicle speedsbelow the threshold may be indicative of vehicles traveling at acongested traffic flow that is less than a current speed limit. Vehiclespeeds at or above the threshold may be indicative of vehicles travelingat a free flow traffic speed around the current speed limit.

At 104, a space-time diagram 704 is generated based upon the locationdata 702 for the road segment. In an embodiment, the space-time diagram704 is generated for an extended road segment comprising the roadsegment and one or more surrounding road segments. The space-timediagram 704 comprises a first axis such as an x axis that representsdistance along the road segment. The space-time diagram 704 comprises asecond axis such as a y axis that represents time. The location data 702of vehicles traveling the road segment (or the extend road segment) isplotted within the space-time diagram 704. In this way, trajectories ofvehicles are represented within the space-time diagram, which correlateto speeds of vehicles traveling the road segment over time. A trajectoryof a vehicle may correspond to plots of vehicle locations of the vehiclealong the road segment over time, and thus is indicative of a speed ofthe vehicle over time along the road segment. In particular, atrajectory of a vehicle may corresponding to consecutive points ofvehicle locations from the same vehicle along the road segment overtime. They are connected by a solid line, and thus indicative of a speedof the vehicle over time along the road segment. Because theconvolutional neural network may be trained to evaluate space-timediagrams in order to identify slowdowns, the convolutional neuralnetwork may identify the slowdown based upon features (e.g., slopes andlocations of trajectories) of the space-time diagram 704, such aschanges to the shape of a trajectory that correspond to a change ofspeed of a vehicle.

A relatively horizontal trajectory (e.g., more parallel to the firstaxis representing distance along the road segment) is indicative of freeflowing traffic (e.g., vehicles traveling at speeds around a speed limitof the road segment). A relatively vertical trajectory (e.g., moreparallel to the second axis representing time, which indicates thatlittle progress is being made over time by a vehicle to travel along theroad segment) is indicative of congested traffic flow (e.g., vehiclestraveling at speeds well below the speed limit). In an embodiment,colors are assigned to vehicle trajectories (e.g., a vehicle trajectorycorresponding to plots of vehicle locations of a vehicle within thespace-time diagram 704) based upon vehicle speeds represented by thevehicle trajectories. For example, a first color such as red may beassigned to vehicle trajectories indicative of vehicles traveling atcongested traffic flow rates (e.g., speeds well below the speed limit),which may be identified based upon vehicle trajectories that are morevertical than horizontal. A second color such as green may be assignedto vehicle trajectories indicative of vehicles traveling at free flowingtraffic rates (e.g., speeds around the speed limit), which may beidentified based upon vehicle trajectories that are more horizontal thanvertical. Other colors may be assigned to other trajectories indicativeof traffic flow rates between the free flowing traffic rate and thecongested traffic flow rate.

FIGS. 2-6 illustrate examples of time-space diagrams that are createdfrom location data of vehicles traveling along road segments. FIG. 2illustrates a first space-time diagram 200 having an x axis 202representing distance along a first road segment and a y axis 204representing time. At the origin of the first space-time diagram 200,the x axis 202 represents a starting position 202 a of the first roadsegment and the y axis 204 represents a starting time 204 a thatoccurred in the past 206. The other end of the x axis 202 represents anending position 202 b of the first road segment. The other end of the yaxis 204 represents a most recent time 204 b of acquired vehicle speeddata (e.g., a more present/current time 208). It may be appreciated thatany other time periods, start times, and end times may be represented bythe y axis 204.

Location data of vehicles traveling the first road segment are plottedwithin the first space-time diagram 200. The plotted location data for aparticular vehicle may represent a trajectory and/or vehicle speed ofthe vehicle over time. For example, a first trajectory 214 of locationdata of a first vehicle indicates that the first vehicle is traveling ata free flowing vehicle traffic rate at a first point in time. This isbecause the first trajectory 214 is more horizontal than vertical andmore parallel to the x axis 202 than the y axis 204, thus indicatingthat the first vehicle is making progress along the first road segmentwithin a reasonable timeframe (e.g., traveling close to a posted speedlimit). A second trajectory 218 of location data of a second vehicleindicates that the second vehicle is traveling at a congested vehicletraffic rate at a second point in time. This is because the secondtrajectory 218 is more vertical than horizontal and more parallel to they axis 204 than the x axis 202, thus indicating that the second vehicleis making little progress along the first road segment over time (e.g.,traveling well below the posted speed limit).

A change in shape of a trajectory corresponds to a change in speed of avehicle (e.g., a rapid change in slope corresponds to a rapidacceleration/deceleration of a vehicle). For example, the firsttrajectory 214 indicates that the first vehicle initially travels at afree flow speed at the first point in time, but at line 210, the firstvehicle slows down and the first trajectory 214 corresponds to congestedtraffic flow at a subsequent point in time. Similarly, the secondtrajectory 218 at a previously point in time indicates that the secondvehicle was initially traveling at the free flow speed, but at line 210,the second vehicle slowed down and the second trajectory 218 correspondsto the congested traffic flow at the second point in time.

As will be described later in further detail, the first space-timediagram 200 can be proceeded to determine probabilities that the firstspace-time diagram 200 illustrates a slowdown or not. With regard to thefirst space-time diagram 200, a slowdown is illustrated where freeflowing vehicle traffic represented by trajectories 212 is coming to asudden slowdown as congested flow vehicle traffic represented bytrajectories 216. Line 210 represents a transition point where thetrajectories of free flowing vehicle traffic transition to trajectoriesof congested flow vehicle traffic. The transition point represents aback of queue of the slowdown where vehicles are starting to experiencethe slowdown and suddenly slowdown. The slowdown and the location of thetransition point (back of queue) is identified using the convolutionalneural network 706 as will be described later in further detail.

FIG. 3 illustrates a second space-time diagram 300 having an x axis 302representing distance along a second road segment and a y axis 304representing time. At the origin of the second space-time diagram 300,the x axis 302 represents a starting position 302 a of the second roadsegment and the y axis 304 represents a starting time 304 a thatoccurred in the past 306. The other end of the x axis 302 represents anending position 302 b of the second road segment. The other end of the yaxis 304 represents a most recent time 304 b of acquired vehicle speeddata (e.g., a more present/current time 308). It may be appreciated thatany other time periods, start times, and end times may be represented bythe y axis 304.

Location data of vehicles traveling the second road segment are plottedwithin the second space-time diagram 300. The plotted location data fora particular vehicle may represent a trajectory and/or vehicle speed ofthe vehicle over time. For example, a first trajectory 314 of locationdata of a first vehicle indicates that the first vehicle is traveling ata free flowing vehicle traffic rate at a first point in time. This isbecause the first trajectory 314 is more horizontal than vertical andmore parallel to the x axis 302 than the y axis 304, thus indicatingthat the first vehicle is making progress along the second road segmentwithin a reasonable timeframe (e.g., traveling close to a posted speedlimit). A second trajectory 318 of location data of a second vehicleindicates that the second vehicle is traveling at a congested vehicletraffic rate at a second point in time. This is because the secondtrajectory 318 is more vertical than horizontal and more parallel to they axis 304 than the x axis 302, thus indicating that the second vehicleis making little progress along the second road segment over time (e.g.,traveling well below the posted speed limit).

A change in shape of a trajectory corresponds to a change in speed of avehicle (e.g., a rapid change in slope corresponds to a rapidacceleration/deceleration of a vehicle). For example, the firsttrajectory 314 indicates that the first vehicle initially travels at afree flow speed at the first point in time, but at line 310, the firstvehicle slows down and the first trajectory 314 corresponds to congestedtraffic flow at a subsequent point in time. Similarly, the secondtrajectory 318 at a previously point in time indicates that the secondvehicle was initially traveling at the free flow speed, but at line 310,the second vehicle slowed down and the second trajectory 318 correspondsto the congested traffic flow at the second point in time.

As will be described later in further detail, the second space-timediagram 300 can be proceeded to determine probabilities that the secondspace-time diagram 300 illustrates a slowdown or not. With regard to thesecond space-time diagram 300, a slowdown is illustrated where freeflowing vehicle traffic represented by trajectories 312 is coming to asudden slowdown as congested flow vehicle traffic represented bytrajectories 316. Line 310 represents a transition point where thetrajectories of free flowing vehicle traffic transition to trajectoriesof congested flow vehicle traffic. The transition point represents aback of queue of the slowdown where vehicles are starting to experiencethe slowdown and suddenly slowdown. The slowdown and the location of thetransition point (back of queue) is identified using the convolutionalneural network 706 as will be described later in further detail.

FIG. 4 illustrates a third space-time diagram 400 having an x axis 402representing distance along a third road segment and a y axis 404representing time. At the origin of the third space-time diagram 400,the x axis 402 represents a starting position 402 a of the third roadsegment and the y axis 404 represents a starting time 404 a thatoccurred in the past 406. The other end of the x axis 402 represents anending position 402 b of the third road segment. The other end of the yaxis 404 represents a most recent time 404 b of acquired vehicle speeddata (e.g., a more present/current time 408). It may be appreciated thatany other time periods, start times, and end times may be represented bythe y axis 404.

Location data of vehicles traveling the third road segment are plottedwithin the second space-time diagram 400. The plotted location data fora particular vehicle may represent a trajectory and/or vehicle speed ofthe vehicle over time. For example, a first trajectory 414 of locationdata of a first vehicle indicates that the first vehicle is traveling ata free flowing vehicle traffic rate at a first point in time. This isbecause the first trajectory 414 is more horizontal than vertical andmore parallel to the x axis 402 than the y axis 404, thus indicatingthat the first vehicle is making progress along the third road segmentwithin a reasonable timeframe (e.g., traveling close to a posted speedlimit). A second trajectory 418 of location data of a second vehicleindicates that the second vehicle is traveling at a congested vehicletraffic rate at a second point in time. This is because the secondtrajectory 418 is more vertical than horizontal and more parallel to they axis 404 than the x axis 402, thus indicating that the second vehicleis making little progress along the third road segment over time (e.g.,traveling well below the posted speed limit).

A change in shape of a trajectory corresponds to a change in speed of avehicle (e.g., a rapid change in slope corresponds to a rapidacceleration/deceleration of a vehicle). For example, the firsttrajectory 414 indicates that the first vehicle initially travels at afree flow speed at the first point in time, but at line 410, the firstvehicle slows down and the first trajectory 414 corresponds to congestedtraffic flow at a subsequent point in time. Similarly, the secondtrajectory 418 at a previously point in time indicates that the secondvehicle was initially traveling at the free flow speed, but at line 410,the second vehicle slowed down and the second trajectory 418 correspondsto the congested traffic flow at the second point in time.

As will be described later in further detail, the third space-timediagram 400 can be proceeded to determine probabilities that the thirdspace-time diagram 400 illustrates a slowdown or not. With regard to thethird space-time diagram 400, a slowdown is illustrated where freeflowing vehicle traffic represented by trajectories 412 is coming to asudden slowdown as congested flow vehicle traffic represented bytrajectories 416. Line 410 represents a transition point where thetrajectories of free flowing vehicle traffic transition to trajectoriesof congested flow vehicle traffic. The transition point represents aback of queue of the slowdown where vehicles are starting to experiencethe slowdown and suddenly slowdown. The slowdown and the location of thetransition point (back of queue) is identified using the convolutionalneural network 706 as will be described later in further detail.

FIG. 5 illustrates a fourth space-time diagram 500 having an x axis 502representing distance along a fourth road segment and a y axis 504representing time. At the origin of the third space-time diagram 500,the x axis 502 represents a starting position 502 a of the fourth roadsegment and the y axis 504 represents a starting time 504 a thatoccurred in the past 506. The other end of the x axis 502 represents anending position 502 b of the fourth road segment. The other end of the yaxis 504 represents a most recent time 504 b of acquired vehicle speeddata (e.g., a more present/current time 508). It may be appreciated thatany other time periods, start times, and end times may be represented bythe y axis 504.

Location data of vehicles traveling the fourth road segment are plottedwithin the fourth space-time diagram 500. The plotted location data fora particular vehicle may represent a trajectory and/or vehicle speed ofthe vehicle over time. For example, a first trajectory 512 of locationdata of a first vehicle indicates that the first vehicle is traveling ata free flowing vehicle traffic rate. This is because the firsttrajectory 512 is more horizontal than vertical and more parallel to thex axis 502 than the y axis 504, thus indicating that the first vehicleis making progress along the fourth road segment within a reasonabletimeframe (e.g., traveling close to a posted speed limit). A secondtrajectory 514 of location data of a second vehicle indicates that thesecond vehicle is traveling at a free flowing vehicle traffic rate. Thisis because the second trajectory 514 is more horizontal than verticaland more parallel to the x axis 502 than the y axis 504, thus indicatingthat the second vehicle is making progress along the fourth road segmentwithin a reasonable timeframe (e.g., traveling close to a posted speedlimit).

As will be described later in further detail, the fourth space-timediagram 500 can be proceeded to determine probabilities that the fourthspace-time diagram 500 illustrates a slowdown or not. With regard to thefourth space-time diagram 500, a slowdown is not illustrated becausemost trajectories 510 are indicative of free flowing vehicle trafficrates. This is because the trajectories 510 are more horizontal thanvertical and more parallel to the x axis 502 than the y axis 504, thusindicating that vehicles are making progress along the fourth roadsegment within a reasonable timeframe (e.g., traveling close to a postedspeed limit).

FIG. 6 illustrates a fifth space-time diagram 600 having an x axis 602representing distance along a fifth road segment and a y axis 604representing time. At the origin of the fifth space-time diagram 600,the x axis 602 represents a starting position 602 a of the fifth roadsegment and the y axis 604 represents a starting time 604 a thatoccurred in the past 606. The other end of the x axis 602 represents anending position 602 b of the fifth road segment. The other end of the yaxis 604 represents a most recent time 604 b of acquired vehicle speeddata (e.g., a more present/current time 608). It may be appreciated thatany other time periods, start times, and end times may be represented bythe y axis 604.

Location data of vehicles traveling the fifth road segment are plottedwithin the fifth space-time diagram 600. The plotted location data for aparticular vehicle may represent a trajectory and/or vehicle speed ofthe vehicle over time. For example, a first trajectory 612 of locationdata of a first vehicle indicates that the first vehicle is traveling ata free flowing vehicle traffic rate. This is because the firsttrajectory 612 is more horizontal than vertical and more parallel to thex axis 602 than the y axis 604, thus indicating that the first vehicleis making progress along the fifth road segment within a reasonabletimeframe (e.g., traveling close to a posted speed limit). A secondtrajectory 614 of location data of a second vehicle indicates that thesecond vehicle is traveling at a free flowing vehicle traffic rate. Thisis because the second trajectory 614 is more horizontal than verticaland more parallel to the x axis 602 than the y axis 604, thus indicatingthat the second vehicle is making progress along the fifth road segmentwithin a reasonable timeframe (e.g., traveling close to a posted speedlimit).

As will be described later in further detail, the fifth space-timediagram 600 can be proceeded to determine probabilities that the fifthspace-time diagram 600 illustrates a slowdown or not. With regard to thefifth space-time diagram 600, a slowdown is not illustrated because mosttrajectories 610 are indicative of free flowing vehicle traffic rates.This is because the trajectories 610 are more horizontal than verticaland more parallel to the x axis 602 than the y axis 604, thus indicatingthat vehicles are making progress along the fifth road segment within areasonable timeframe (e.g., traveling close to a posted speed limit).

At 105, the convolutional neural network 706 is used to process thespace-time diagram 704 to identify a slowdown 707, if present. Theconvolutional neural network 706 is trained and configured to identify,extract, and evaluate features of space-time diagrams in order toidentify slowdowns represented by the space-time diagrams. The featuresmay correspond to shapes of trajectories, angles/slopes of trajectories,counts or percentages of trajectories having certain features, locationsof trajectories, changes in slope of trajectories, colors oftrajectories, and/or a wide variety of other features that areindicative of slowdowns being illustrated within space-time diagrams ornot. In this way, the convolutional neural network 706 processes thespace-time diagram 704 to identify the slowdown 707, if present.

In an embodiment, the space-time diagram 704 is processed using theconvolutional neural network 706 to output a first probability that thespace-time diagram 704 illustrates a slowdown. The convolutional neuralnetwork 706 may also output a second probability that the space-timediagram 704 does not illustrate a slowdown. The convolutional neuralnetwork 706 is trained to utilize image recognition functionality toevaluate features of space-time diagrams to output probabilities thatthe space-time diagrams illustrate slowdowns based upon the features(e.g., space-time diagrams labeled as illustrating and not illustratingslowdowns are used to train the convolutional neural network to identifyfeatures indicative of slowdowns being illustrated or not withinspace-time diagrams). The features may correspond to shapes oftrajectories, angles/slopes of trajectories, counts or percentages oftrajectories having certain features, locations of trajectories, changesin slope of trajectories, colors of trajectories, and/or a wide varietyof other features that are indicative of slowdowns being illustratedwithin space-time diagrams or not.

In an embodiment, at 106, a regression convolutional neural network 706is used to identify one or more transitions points 708 depicted by thespace-time diagram 704. The transition points 708 are where free-flowingvehicle speeds transition to congested vehicle speeds. In particular,the regression convolutional neural network 706 is trained to identifypixels within the space-time diagram 704 that represent transitionpoints (e.g., a back of queue), such as based upon featurescorresponding to changes in slopes of trajectories and locations of thechanges in slope. In an example, the regression convolutional neuralnetwork 706 identifies a time series of transition points. A Kalmanfilter is executed upon the time series of transition points to identifyan accurate current transition point and to predict future transitionpoint locations. With having known transition point locations, vehiclespeeds are separated into free flow and congested speed clusters. If adifference in median speed of the clusters is greater than a thresholdspeed, then the slowdown is categorized as a dangerous slowdown or otherslowdown category based upon other threshold speeds.

If the probabilities are above a threshold probability and thus indicatethat a slowdown is illustrated by the space-time diagram 704, then thecurrent transition point from free-flow speeds to congested speeds isfound using a regression convolutional neural network. This transitionpoint is then found for different times and used to construct a timeseries of transition points. A Kalman filter is applied to this timeseries of transition points to find a more accurate transition point.Additionally, this Kalman filter also predicts the change of thetransition point along the road segment over time.

With the transition point location on the road segment accurately known,the free-flowing and congested vehicle speeds can be separatedaccurately into two different speed clusters. In an embodiment, afilter, such as a Hampel filter, is applied to each speed cluster toremove outlier vehicle speeds. A difference between a first medianvehicle speed of the first cluster and a second median vehicle speed ofthe second cluster (a speed delta between free flow and congestedtraffic) is determined. If the difference exceeds a speed threshold,then the dangerous slowdown is identified. Upon identifying the slowdownalong the road segment, properties 712 of the slowdown are identifiedbased upon the space-time diagram 704, the clusters, location data,and/or vehicle speed data. The transition point may be converted intolongitude and latitude values indicative of a location of the back endof queue where vehicles are suddenly slowing down due to the slowdown.Other properties can be determined such as a time of the slowdown, apredicted time that the slowdown will dissipate, a future location ofthe slowdown, etc.

In an embodiment, the transition point is identified using a regressionconvolutional neural network. The regression convolutional neuralnetwork may be trained to identify pixels within a space-time diagramthat represent a transition point (a back of queue). The regressionconvolutional neural network is tracked to search for transition pointsfor different times, and outputs positions of the transition points (theback of queue) at different times. A time series of transition pointsmay be constructed. A Kalman filter is applied to the time series oftransition points to determine a transition point between free flowingvehicle traffic and congested flow vehicle traffic along the roadsegment due to the slowdown and predict a future location of thetransition point. This will provide a more accurate location of thetransition point (the back of queue) at various times. Vehicle speedsmay be separate into separate clusters using the transition point (e.g.,vehicle speeds collected from vehicles yet to reach the transition pointmay be clustered in a first cluster and vehicle speeds collected fromvehicles that have reached the transition point may be clustered into asecond cluster). A difference between the transition point between freeflowing vehicle traffic and congested flow vehicle traffic along theroad segment due to the slowdown and predict a future location(s) of thetransition point are determined. A Hampel filter may be applied to theclusters to remove outlier vehicle speeds. The slowdown is identifiedbased upon the difference between the first cluster median and thesecond cluster median exceeding a speed threshold (e.g., exceeding 65kph).

In an embodiment, additional factors may be taken into account whendetermining whether a slowdown exists along the road segment. A roadcondition (e.g., construction, an accident, etc.) and/or a weathercondition (e.g., snow or rain) for the road segment is used as a factorfor determining whether there is a slowdown. Also, historic slowdownoccurrences can be taken into account. For example, occurrences ofslowdowns for the road segment are tracked as historical data. Thehistorical data is used as a factor for determining whether there is aslowdown (e.g., a road segment having frequent historic occurrences ofslowdowns may have a probability of a slowdown increased by a factor ofhow frequently slowdowns occurred for the road segment).

At 108, a notification of the slowdown is constructed and transmittedover a network to a computing device associated with a driver of avehicle that is to travel the road segment during the slowdown. In anembodiment, the notification is transmitted to computing devices ofvehicles within a threshold distance of a location of the slowdown. Thenotification may be transmitted to computing devices associated withvehicles that are traveling routes that will encounter the slowdownduring a predicted duration of the slowdown. The notification may beconstructed to comprise a description of the slowdown (e.g., a number ofvehicles affected), an alternative route for avoiding the slowdown, arelatively precise location of the slowdown (e.g., the back of queuelocation), a current distance of a vehicle to the location of theslowdown, a timeframe of the slowdown, a predicted timeframe of theslowdown dissipating, a predicted future location of the slowdown (e.g.,a location of the back of queue by the time the vehicle will be within athreshold distance of the slowdown), etc. Various visual and audiblenotifications/alerts may be provided by the notification through thecomputing device. In this way, drivers are provided with adequate noticeof slowdowns so that drivers have ample time to safely react to theslowdowns.

In an embodiment, a particular type/degree of slowdown, such as adangerous slowdown, a moderate slowdown, a continuous spectrum ofdifferent degrees of slowdowns, etc. is detected. A type/degree ofslowdown may be detected based upon certain properties of the slowdown,the time-space diagram, and/or vehicle location data. For example, adangerous slowdown is detected if a difference between free flowingtraffic speed and congested flow traffic speed (e.g., a transition fromfree flowing to congested flow traffic, such as a backend of queue ofthe slowdown where vehicle are abruptly slowing down) is greater than athreshold such as 65 kph or any other threshold speed value. A dangerousslowdown relates to a lack of opportunity for a driver to adequatelyslowdown in time, which can be identified by slopes of vehicletrajectories within the space-time diagram 704 that correspond tocertain amounts of deceleration over short distances. In anotherexample, a continuous spectrum or multiple types/degrees of slowdownscan be identified (e.g., very dangerous slowdown corresponding to 70kph, a dangerous slowdown corresponding to 65 kph, a moderatelydangerous slowdown corresponding to 50 kph, etc.), where each type ofslowdown corresponds to a degree or severity of danger of a slowdown.The different degrees/types of slowdowns can be identified based upondifferent threshold speed values or slopes of vehicle trajectories(e.g., a steeper slope may be indicative of a more dangerous type ofslowdown).

FIG. 8 is an illustration of a scenario 800 involving an examplenon-transitory machine readable medium 802. The non-transitory machinereadable medium 802 may comprise processor-executable instructions 812that when executed by a processor 816 cause performance (e.g., by theprocessor 816) of at least some of the provisions herein. Thenon-transitory machine readable medium 802 may comprise a memorysemiconductor (e.g., a semiconductor utilizing static random accessmemory (SRAM), dynamic random access memory (DRAM), and/or synchronousdynamic random access memory (SDRAM) technologies), a platter of a harddisk drive, a flash memory device, or a magnetic or optical disc (suchas a compact disk (CD), a digital versatile disk (DVD), or floppy disk).The example non-transitory machine readable medium 802 storescomputer-readable data 804 that, when subjected to reading 806 by adevice 808 (e.g., a read head of a hard disk drive, or a read operationinvoked on a solid-state storage device), express theprocessor-executable instructions 812. In some embodiments, theprocessor-executable instructions 812, when executed cause performanceof operations 814, such as at least some of the example method 100 ofFIG. 1, for example. In some embodiments, the processor-executableinstructions 812 are configured to cause implementation of a system,such as at least some of the example system 700 of FIG. 7, for example.

Although the subject matter has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described above.Rather, the specific features and acts described above are disclosed asexample forms of implementing at least some of the claims.

As used in this application, the terms “component,” “module,” “system”,“interface”, and/or the like are generally intended to refer to acomputer-related entity, either hardware, a combination of hardware andsoftware, software, or software in execution. For example, a componentmay be, but is not limited to being, a process running on a processor, aprocessor, an object, an executable, a thread of execution, a program,and/or a computer. By way of illustration, both an application runningon a controller and the controller can be a component. One or morecomponents may reside within a process and/or thread of execution and acomponent may be localized on one computer and/or distributed betweentwo or more computers.

Furthermore, the claimed subject matter may be implemented as a method,apparatus, or article of manufacture using standard programming and/orengineering techniques to produce software, firmware, hardware, or anycombination thereof to control a computer to implement the disclosedsubject matter. The term “article of manufacture” as used herein isintended to encompass a computer program accessible from anycomputer-readable device, carrier, or media. Of course, manymodifications may be made to this configuration without departing fromthe scope or spirit of the claimed subject matter.

FIG. 9 and the following discussion provide a brief, general descriptionof a suitable computing environment to implement embodiments of one ormore of the provisions set forth herein. The operating environment ofFIG. 9 is only one example of a suitable operating environment and isnot intended to suggest any limitation as to the scope of use orfunctionality of the operating environment. Example computing devicesinclude, but are not limited to, personal computers, server computers,hand-held or laptop devices, mobile devices (such as mobile phones,Personal Digital Assistants (PDAs), media players, and the like),multiprocessor systems, consumer electronics, mini computers, mainframecomputers, distributed computing environments that include any of theabove systems or devices, and the like.

Although not required, embodiments are described in the general contextof “computer readable instructions” being executed by one or morecomputing devices. Computer readable instructions may be distributed viacomputer readable media (discussed below). Computer readableinstructions may be implemented as program modules, such as functions,objects, Application Programming Interfaces (APIs), data structures, andthe like, that perform particular tasks or implement particular abstractdata types. Typically, the functionality of the computer readableinstructions may be combined or distributed as desired in variousenvironments.

FIG. 9 illustrates an example of a system 900 comprising a computingdevice 912 configured to implement one or more embodiments providedherein. In one configuration, computing device 912 includes at least oneprocessor 916 and memory 918. Depending on the exact configuration andtype of computing device, memory 918 may be volatile (such as RAM, forexample), non-volatile (such as ROM, flash memory, etc., for example) orsome combination of the two. This configuration is illustrated in FIG. 9by dashed line 914.

In other embodiments, device 912 may include additional features and/orfunctionality. For example, device 912 may also include additionalstorage (e.g., removable and/or non-removable) including, but notlimited to, magnetic storage, optical storage, and the like. Suchadditional storage is illustrated in FIG. 9 by storage 920. In oneembodiment, computer readable instructions to implement one or moreembodiments provided herein may be in storage 920. Storage 920 may alsostore other computer readable instructions to implement an operatingsystem, an application program, and the like. Computer readableinstructions may be loaded in memory 918 for execution by processor 916,for example.

The term “computer readable media” as used herein includes computerstorage media. Computer storage media includes volatile and nonvolatile,removable and non-removable media implemented in any method ortechnology for storage of information such as computer readableinstructions or other data. Memory 918 and storage 920 are examples ofcomputer storage media. Computer storage media includes, but is notlimited to, RAM, ROM, EEPROM, flash memory or other memory technology,CD-ROM, Digital Versatile Disks (DVDs) or other optical storage,magnetic cassettes, magnetic tape, magnetic disk storage or othermagnetic storage devices, or any other medium which can be used to storethe desired information and which can be accessed by device 912.Computer storage media does not, however, include propagated signals.Rather, computer storage media excludes propagated signals. Any suchcomputer storage media may be part of device 912.

Device 912 may also include communication connection 926 that allowsdevice 912 to communicate with other devices. Communication connection926 may include, but is not limited to, a modem, a Network InterfaceCard (NIC), an integrated network interface, a radio frequencytransmitter/receiver, an infrared port, a USB connection, or otherinterfaces for connecting computing device 912 to other computingdevices. Communication connection 926 may include a wired connection ora wireless connection. Communication connection 926 may transmit and/orreceive communication media.

The term “computer readable media” may include communication media.Communication media typically embodies computer readable instructions orother data in a “modulated data signal” such as a carrier wave or othertransport mechanism and includes any information delivery media. Theterm “modulated data signal” may include a signal that has one or moreof its characteristics set or changed in such a manner as to encodeinformation in the signal.

Device 912 may include input device 924 such as keyboard, mouse, pen,voice input device, touch input device, infrared cameras, video inputdevices, and/or any other input device. Output device 922 such as one ormore displays, speakers, printers, and/or any other output device mayalso be included in device 912. Input device 924 and output device 922may be connected to device 912 via a wired connection, wirelessconnection, or any combination thereof. In one embodiment, an inputdevice or an output device from another computing device may be used asinput device 924 or output device 922 for computing device 912.

Components of computing device 912 may be connected by variousinterconnects, such as a bus. Such interconnects may include aPeripheral Component Interconnect (PCI), such as PCI Express, aUniversal Serial Bus (USB), firewire (IEEE 1394), an optical busstructure, and the like. In another embodiment, components of computingdevice 912 may be interconnected by a network. For example, memory 918may be comprised of multiple physical memory units located in differentphysical locations interconnected by a network.

Those skilled in the art will realize that storage devices utilized tostore computer readable instructions may be distributed across anetwork. For example, a computing device 930 accessible via a network928 may store computer readable instructions to implement one or moreembodiments provided herein. Computing device 912 may access computingdevice 930 and download a part or all of the computer readableinstructions for execution. Alternatively, computing device 912 maydownload pieces of the computer readable instructions, as needed, orsome instructions may be executed at computing device 912 and some atcomputing device 930.

Various operations of embodiments are provided herein. In oneembodiment, one or more of the operations described may constitutecomputer readable instructions stored on one or more computer readablemedia, which if executed by a computing device, will cause the computingdevice to perform the operations described. The order in which some orall of the operations are described should not be construed as to implythat these operations are necessarily order dependent. Alternativeordering will be appreciated by one skilled in the art having thebenefit of this description. Further, it will be understood that not alloperations are necessarily present in each embodiment provided herein.Also, it will be understood that not all operations are necessary insome embodiments.

Further, unless specified otherwise, “first,” “second,” and/or the likeare not intended to imply a temporal aspect, a spatial aspect, anordering, etc. Rather, such terms are merely used as identifiers, names,etc. for features, elements, items, etc. For example, a first object anda second object generally correspond to object A and object B or twodifferent or two identical objects or the same object.

Moreover, “exemplary” is used herein to mean serving as an example,instance, illustration, etc., and not necessarily as advantageous. Asused herein, “or” is intended to mean an inclusive “or” rather than anexclusive “or”. In addition, “a” and “an” as used in this applicationare generally be construed to mean “one or more” unless specifiedotherwise or clear from context to be directed to a singular form. Also,at least one of A and B and/or the like generally means A or B and/orboth A and B. Furthermore, to the extent that “includes”, “having”,“has”, “with”, and/or variants thereof are used in either the detaileddescription or the claims, such terms are intended to be inclusive in amanner similar to the term “comprising”.

Also, although the disclosure has been shown and described with respectto one or more implementations, equivalent alterations and modificationswill occur to others skilled in the art based upon a reading andunderstanding of this specification and the annexed drawings. Thedisclosure includes all such modifications and alterations and islimited only by the scope of the following claims. In particular regardto the various functions performed by the above described components(e.g., elements, resources, etc.), the terms used to describe suchcomponents are intended to correspond, unless otherwise indicated, toany component which performs the specified function of the describedcomponent (e.g., that is functionally equivalent), even though notstructurally equivalent to the disclosed structure. In addition, while aparticular feature of the disclosure may have been disclosed withrespect to only one of several implementations, such feature may becombined with one or more other features of the other implementations asmay be desired and advantageous for any given or particular application.

What is claimed is:
 1. A method involving a computing device comprisinga processor, and the method comprising: executing, on the processor,instructions that cause the computing device to perform operations, theoperations comprising: evaluating location data received from vehiclestraveling a road to identify a road segment associated with vehiclespeeds below a threshold; generating a space-time diagram comprising afirst axis representing distance along the road segment and a secondaxis representing time, wherein location data associated with thevehicles traveling the road segment are plotted within the space-timediagram; processing the space-time diagram using a convolutional neuralnetwork trained to utilize image recognition functionality to detectwhether space-time diagrams illustrate slowdowns of the vehicles; andtransmitting a notification of a slowdown associated with the space-timediagram to the computing device associated with a driver of a vehiclethat is to travel the road segment.
 2. The method of claim 1, theoperations comprising: assigning colors to vehicle trajectories withinthe space-time diagram, wherein each color corresponds to a differentrange of vehicle speeds.
 3. The method of claim 1, the operationscomprising: processing the space-time diagram using the convolutionalneural network to output a second probability that the space-timediagram does not illustrate a slowdown; and determining whether there isthe slowdown based upon the second probability.
 4. The method of claim1, comprising: executing a regression convolutional neural network toconstruct a time series of transition points based upon featuresextracted from the space-time diagram; and applying a Kalman filter todetermine a transition point between free flowing vehicle traffic andcongested flow vehicle traffic along the road segment due to theslowdown and predict a future location of the transition point.
 5. Themethod of claim 4, comprising: separating vehicle speeds into separateclusters using the transition point; determining a difference between afirst median of a first cluster representing free flow traffic speedsand a second median of a second cluster representing slowdown trafficspeeds; and identifying the slowdown based upon the difference betweenthe first median and the second median exceeding a speed threshold. 6.The method of claim 5, comprising: evaluating the first cluster and thesecond cluster to identify the transition point where a back of queue ofthe slowdown is located along the road segment.
 7. The method of claim5, comprising: applying a Hampel filter to the first cluster and thesecond cluster to remove outliers vehicle speeds.
 8. The method of claim1, comprising: constructing the notification to comprise a location of atransition point between free flowing vehicle traffic and congested flowvehicle traffic along the road segment due to the slowdown.
 9. Themethod of claim 1, comprising: evaluating the space-time diagram andvehicle speed data to predict a time frame of the slowdown dissipating;and constructing the notification to comprise the time frame.
 10. Themethod of claim 1, comprising: evaluating the space-time diagram andvehicle speed data to predict a future location of a transition pointbetween free flowing vehicle traffic and congested flow vehicle trafficalong the road segment due to the slowdown; and constructing thenotification to comprise the future location.
 11. The method of claim 1,comprising: constructing the notification to comprise a timeframe of theslowdown.
 12. A computing device comprising: a processor; and memorycomprising processor-executable instructions that when executed by theprocessor cause performance of operations, the operations comprising:evaluating location data received from vehicles traveling a road toidentify a road segment associated with vehicle speeds below athreshold; generating a space-time diagram comprising a first axisrepresenting distance along the road segment and a second axisrepresenting time, wherein location data associated with the vehiclestraveling the road segment are plotted within the space-time diagram;processing the space-time diagram using a convolutional neural networktrained to utilize image recognition functionality to detect whetherspace-time diagrams illustrate slowdowns of the vehicles; andtransmitting a notification of a slowdown associated with the space-timediagram to the computing device associated with a driver of a vehiclethat is to travel the road segment.
 13. The computing device of claim12, the operations comprising: constructing the notification to comprisea location of a transition point between free flowing vehicle trafficand congested flow vehicle traffic along the road segment due to theslowdown, wherein the transition point along the road segment isconverted into longitudinal and latitude values to identify thelocation.
 14. The computing device of claim 12, the operationscomprising: identifying at least one of a road condition or a weathercondition for the road segment; and factoring in the least one of theroad condition or the weather condition when determining whether thereis a slowdown along the road segment.
 15. The computing device of claim12, the operations comprising: tracking occurrences of slowdowns for theroad segment as historical data; and factoring in the historical datawhen determining whether there is a slowdown along the road segment. 16.The computing device of claim 12, the operations comprising:transmitting the notification to computing devices associated withvehicles within a threshold distance of a location of the slowdown. 17.A non-transitory machine readable medium having stored thereonprocessor-executable instructions that when executed cause performanceof operations, the operations comprising: evaluating location datareceived from vehicles traveling a road to identify a road segmentassociated with vehicle speeds below a threshold; generating aspace-time diagram comprising a first axis representing distance alongthe road segment and a second axis representing time, wherein locationdata associated with the vehicles traveling the road segment are plottedwithin the space-time diagram; processing the space-time diagram using aconvolutional neural network trained to utilize image recognitionfunctionality to detect whether space-time diagrams illustrate slowdownsof the vehicles; and transmitting a notification of a slowdownassociated with the space-time diagram to the computing deviceassociated with a driver of a vehicle that is to travel the roadsegment.
 18. The computing device of claim 17, the operationscomprising: transmitting the notification to computing devicesassociated with vehicles that are traveling routes that will encounterthe slowdown during a predicted duration of the slowdown.
 19. Thecomputing device of claim 17, the operations comprising: clusteringvehicle speeds represented within the space-time diagram using aclustering algorithm; determining a difference between a first median ofa first cluster representing free flow traffic speeds and a secondmedian of a second cluster representing slowdown traffic speeds; andidentifying the slowdown based upon the difference exceeding a speedthreshold.
 20. The computing device of claim 19, the operationscomprising: evaluating the first cluster and the second cluster toidentify a transition point where a back of queue of the slowdown islocated along the road segment.